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/* Language-level data type conversion for Treelang.

   This is a very slightly modified copy of c-convert.c.

   Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2007

   Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 3, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

/* This file contains the functions for converting C expressions

   to different data types.  The only entry point is `convert'.

   Every language front end must have a `convert' function

   but what kind of conversions it does will depend on the language.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "diagnostic.h"

#include "tree.h"

#include "flags.h"

#include "convert.h"

#include "toplev.h"

#include "langhooks.h"

/* Change of width--truncation and extension of integers or reals--

   is represented with NOP_EXPR.  Proper functioning of many things

   assumes that no other conversions can be NOP_EXPRs.

   Conversion between integer and pointer is represented with CONVERT_EXPR.

   Converting integer to real uses FLOAT_EXPR

   and real to integer uses FIX_TRUNC_EXPR.

   Here is a list of all the functions that assume that widening and

   narrowing is always done with a NOP_EXPR:

     In convert.c, convert_to_integer.

     In c-typeck.c, build_binary_op (boolean ops), and

        c_common_truthvalue_conversion.

     In expr.c: expand_expr, for operands of a MULT_EXPR.

     In fold-const.c: fold.

     In tree.c: get_narrower and get_unwidened.  */

/* Create an expression whose value is that of EXPR,

   converted to type TYPE.  The TREE_TYPE of the value

   is always TYPE.  This function implements all reasonable

   conversions; callers should filter out those that are

   not permitted by the language being compiled.  */

tree

convert (tree type, tree expr)

{

  tree e = expr;

  enum tree_code code = TREE_CODE (type);

  if (type == TREE_TYPE (expr)

      || TREE_CODE (expr) == ERROR_MARK

      || code == ERROR_MARK || TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)

    return expr;

  if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)))

    return fold_build1 (NOP_EXPR, type, expr);

  if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)

    return error_mark_node;

  if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)

    {

      error ("void value not ignored as it ought to be");

      return error_mark_node;

    }

  if (code == VOID_TYPE)

    return build1 (CONVERT_EXPR, type, e);

  if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)

    return fold (convert_to_integer (type, e));

  if (code == BOOLEAN_TYPE)

    {

      tree t = expr;

      /* If it returns a NOP_EXPR, we must fold it here to avoid

         infinite recursion between fold () and convert ().  */

      if (TREE_CODE (t) == NOP_EXPR)

        return fold_build1 (NOP_EXPR, type, TREE_OPERAND (t, 0));

      else

        return fold_build1 (NOP_EXPR, type, t);

    }

  if (code == POINTER_TYPE || code == REFERENCE_TYPE)

    return fold (convert_to_pointer (type, e));

  if (code == REAL_TYPE)

    return fold (convert_to_real (type, e));

  if (code == COMPLEX_TYPE)

    return fold (convert_to_complex (type, e));

  if (code == VECTOR_TYPE)

    return fold (convert_to_vector (type, e));

  error ("conversion to non-scalar type requested");

  return error_mark_node;

}